Process for developing positive diazo prints



Jan. 19, 1932. 1.. P. F. VAN DER GRINTEN ET AL 1,841,553

PROCESS FOR DEVELOPING POSITIVE DIAZO PRINTS Filed Aug. 11, 1928 Inve'nfor-s:

L- P. F van Jar GrzQnZe-n and If. :11]. van cler- Grlnten By '0-Attorney Patented Jan. 19, 1932 UNITED STATES PATENT OFFICE LODHWIJ'K2mm MS van mm GBINTEN AND KARE JAIN JOSE! van nan GBIN'IEN,

or v'nnno, umnnnnmns, Lmnnae, nnmnnmnns ASBIGNOBS TO FRANS VAN DERORINTEN, OF VENLO,

PROCESS FOR DEVELOPING POSITIVE DIAZO PRINTS Application fled August 11,1828, Serial No. 299,042, and in the Netherlands August 22, 1827.

It is common knowled e that the positive diazo printin process is usedon two properties of the iazo compounds:

() Their sensitiveness to li ht. The diazo 6 compounds are decomposedprobably and pn 1lzhe whole into phenols) by exposure to i (b) Theirproperty of forming azo dyes with substances known as azo-dye compo- 10nents.

Reaction (6 takes place mostly with the co-operation o alkalis. In thephotographic diazo printing process, a film containing a diazo compoundand generally disposed on aper is exposed to light under a transparentimage, drawin or tracing, so that the diazo com ound is ecomposed onthose areas of the lm which are reached by light.

An.azo dye is formed in the areas which are unaffected by light (and inwhich the diazo compound has remained unaltered) by treating the exposedfilm with an azo-dye component and alkali, while the areas which havebeen exposed to light remain colourless when treated in this manner. Theimage is simultaneously fixed, because after being subjected to thistreatment (which may be also considered as a developing treatment) theimage-forming areas (now containing a dye) as well as the backgroundreached by light, are stable under any further action thereof. Thepositive diazorinting process does not involve a separate ing operation,which is necessary in most of the other photographic processes and whichusually consists in removing either non-decomposed light-sensitiveinitial materials or certain substances formed by the action of light.In the positive photo graphic diazo printing process, the develop ingoperation (which is simultaneously a fixing operation) consistsexclusively in an addltion of substances. It is in fact sufiicient toadd an alkali for developing purposes when the azo-dye components areinitially embodied in the light-sensitive film, this being made possiblein practice by using certain diazo compounds such as for example diazoanhydrides. The simplest known manner in which the alkali may be addedis to subject the exposed sensitive film to the action of gaseousammonia, the prints being disposed in a developing tank vcontainingammonia vapour. The advantage of this method of proceeding is thatdeveloping baths are dispensed with, so that the pictures thus developedneed not be dried.

This developing method has however the following disadvantages:

(a) The developing operation is comparatively lengthy, especially in thewinter. At low temperature, the prints must remain in theammonia-charged atmosphere for half an hour or more in order to be fullydeveloped.

(1)) When no complicated mechanical apparatus is used, this developingoperation is highly tedious because of the unpleasant and lIlJllI'lOllSalkaline vapours.

The developing tanks must therefore he often in the open and the printsdeveloped smell of ammonia for a long time.

These two main disadvantages are the rea son why the diazo printingprocess with what is known as dry development is not used in practice aswidely as the simplicity of the process might have warranted.

The above disadvantages are not to be found in the method of developingdiazo prints in baths (described for example in Eders Handbuch derPhotographic, 1899, pages 563-565, and in Photographisehe Korrespondenz,1895, pages 284-285) because (a) the print may be developed in a fewseconds, and (b) non-volatile alkalis may be used which evolve nooffensive and injurious vapours.

This method however lacks the characteristic advantages inherent in drydevelopment with the aid of vapours. Moreover, a difliculty involved inthe use of baths is that the always more or less soluble azo-dyes mergeone into the other, with the result that the images obtained are notsharp and the clearness of the background is affected.

The present process has the advantages of both the methods described inthe foregoing while their disadvantages are entirely avoided. Accordingto the present invention, an extremely thin layer of an alkaline liquid(which if necessary may contain an azo-d e component) is uniformlyspread over the whole area to be developed. Friction may be avoided, inwhich case the procedure con sists in applying an extremely thin layerof the developing liquid on the surface to be developed. This makes itpossible:

(a) To develop in a few seconds;

(6) To avoid offensive vapours by using non-volatile alkalis;

(c) To use a very thin layer of liquid, so that the prints remain dryand the colours do not merge;

(d) To use diazo compounds (by applying the alkaline developer togetherwith the azodye components) which cannot be used (or can be used onlyunder certain conditions) together with azo-dye components in thelight-sensitive film, whereby the selection of diazo compounds is verylarge.

In the accompanying drawing, the single figure is a side view, partly invertical section, of an apparatus for applying the developer.

This apparatus, which is of extremely simple character, comprises twovertically superposed and rubber-covered rolls a and b, the lower roll 5revolving in a trough 0 containing the developing liquid and the upperroll bearing on the lower one by gravity or being pressed (hard whennecessary) thereon by suitable means such as for example screws (0)acting upon the bearings of the roll. The lower roll is driven while theupper roll is preferably moved at the same peripheral velocity so thatthere is no friction at the line of contact.

The lower rubber roll 6 collects, while rotating. developing liquid fromthe trough c and l'fli-I V \'S it to the line of contact of the tworolls. Here the liquid is practically entirely retained and flows backuniformly.

This extremely simple apparatus comprises moreover a small table ddisposed in front of the upper roll and fitted with a simple guiding andflattening device 8 to prevent creases from being formed. A stripper maybe advantageously provided to prevent the paper from adhering to therolls. This stripper may be constituted by blades f projecting as far asthe grooves g of the rolls.

)Vhen a print is passed between the two rolls with the side to bedeveloped facing dmvmvards, the said side is wetted by the developinliquid for a very short instant'and is pressed between the two rubberrolls immediately after. To this end, the print it is laid on the table(1 with the image side upwards and is pushed between the upper roll aand the flattening device 8; the roll a picks up the print and conveysit through the rolls a and b The print comes out at the other sidebetween the rolls; it carries a sufficient quantity of developer and ispractically dry. The chemical development reaction now takes placewithin a very short time (a few minutes at most) in the film thustreated. There is however no necessity to wait, because the printdevelops of itself without further supervision.

Four metres of prints may be easily developed per minute when the widthis suitable (usually 100 cm.). This rate of operation may beconsiderably increased by using a very concentrated developing liquid;it is also possible however, to work, if required, at a slower rate byusing more dilute developers.

For small installations this simple apparatus may be replaced bysmaller, sim ler and cheaper means with the aid of whic it is likewisepossible to provide the light print with a uniform thin layer ofdeveloping li uid.

he developers which may be used according to this invention are aqueoussolutions of 35 alkalis or alkaline-reacting substances, mixed ifnecessary with azo-dye components such as phloroglucinol, resorcinol,resorcinie acids, naphthols, phenols, naphthol-sulphonic acids and thelike. Should the light-sensitive film be devoid of substances preventingthe prints from turning yellow, such substances may also be added to thedeveloper.

The substances which prevent the prints from turning yellow may beincorporated in the light-sensitive film as well as in the developingliquid. As a general rule, reducing substances which are stable in anacid medium are preferably used in the. lightsensitive film and thosewhich are stable in an alkali medium are used in the developing liquid.

The alkaline substances used may advantageously be potassium carbonate,sodium carbonate and ammonium carbonate (the latter not so much to berecommended because it has a smell of ammonia) preferably mixed withbuffer salts such as secondary phosphates, secondary citrates andgenerally salts of polyvalent weak acids and the like.

Bufl'er salts are salts by which the intensity of the alkaline reactionis decreased without affecting the potential alkaline reaction,especially salts of polyvalent acids, such as phosphoric acid, citricacid and the like, and salts having a neutral reaction, such assecondary sodium phosphate; which salt, for instance, if added to analkali solution, forms tertiary phosphate. Said salt has an alkalinereaction, but in the presence of an excess of secondary salt theconcentration of the OH-ions, which causes the intensity of the alkalinereaction, is very considerably decreased with respect to the originalalkali solution and yet its alkaline action (capacity 1 of neutralizingacids) remains the same.

In order that the printing may be as uniform as possible, a wettingagent such as alcohol, glycerine, Turkey-red oil and the like may beadded to the developing liquid.

Ewample 1.-Prints obtained by exposing diazo-printing paper thelight-sensitive film of which contains1.dimethylamino.2.chlorobenzene.4.diazonium chloride, or4.diethylamino-benzol-diazonium chloride are printed with a developer bybein guided between the rubber-covered rolls escribed in the foregoing.The said developer is an aqueous solution of 20 parts by weight ofotassium carbonate, 30 arts by weight of 'sodium phosphate an 1.2 partsby weight of phloroglucinol, so that the print is developed. Positiveimages are thus obtained in dark to black colour on a light background.In the developer, the 1.2 parts by weight of phloroglucinol may be repaced by 4 parts by weight of resorcinol, 5 parts by weight offl-naphthol, 5 parts by weight of B-oxy-naphthoic acid anilide, 3 partsby weight of 2.7.dioxynapthaline and the like. These are then dissolvedin quantities of soda lye sufficient for dissolution and yield images invarious dark colours.

In a similar manner, the otassium carbonate may be replaced by so iumcarbonate or ammonium carbonate while disodium phosphate may be replacedby disodium citrate or the like.

The following may be added to the developer to prevent t e print fromturning yellow: 0.4% of formalin or 1% of urotropin and the like' or 5%of glucose, 2% of sodium lactate, 0.1% of pyrogallol.

The uniform spreading of the developer on the pa r is assisted with 5%of methylated alco 01 or 3% of glycerine or 1% of T urkey-red oil andthe like.

Example Q.A solution is made, which contains 1.8% of1.diethyl-aminobenzoL4.diazonium chlorostannate and 1% of potassiumsulphate. The solution is spread on paper and the like, and dried. Afterexposure under a drawing of transparent paper, a thin layer of anaqueous solution of 5% of potassium carbonate, 0.5% of phloroglucinol,0.5% of resorcinol, 10% of potassium chloride, 10% of sodium citrate,10% sodium hyposulphate and 10% of glucose is uniformly spread over thewhole surface of the rint with the apparatus shown. An entirely lackpicture is obtained, which is very stable against any tendency to becomeyellow, which would not be the case without the reducing means (citrate,h posulphite and glucose).

Example 3. thin layer of a developing liquid constituted by an aqueoussolution of 40 parts by weight of potassium carbonate and 60 parts byweight of disodium phosphate is spread as in Example 1 on printsobtained by exposing diazo printing papers containing 1.5 parts byweight of 2.7 .dioxynaphthaline and 3% of oxalic acid to 5 parts byweight of 1.dimethylamino.3.5.xylol.4.diazonium chlorostannate; or 0.5parts by weight of phloroglucinol and 3% of oxalic acid, or 1.5 parts byweight of triketohexamethylenetrioxym, 0.3 parts by weight ofhydroxylamine chloride and 2 parts by weight of tartaric acid to 5 artsby weight of 1.dimethylamino.3.5.x lo .4.diazonium chlorostannate; orthe hy roxylamine compound of 0.2 parts by weight of phlorogluclnol andtwo parts by wei ht of tartaric acid to 1.5 arts by weight ofdimethylaminobenzene.4. iazonium chlorostannate; or combinations ofthese BXamElES. All methods of printin described in xample 1 are also aplica le to the present example.

mample 4.Prints obtained by exposing diazo prlnt papers made of diazoanhydrides with azo dye components are printed as in Examples 1, 2 or 3and treated with a developer as in Example 3. All methods of printingdescribed in Example 1 are applicable to this example.

What we claim is 1. The process for developing direct positive diazoprints which consists in impressing upon the surface to be developed analkaline liquid containing an azo-dyestuif component and a reducingagent non-decomposable by alkali, in the form of a uniformly thin film.

2. The process for developing direct positive diazo prints whichconsists in impressing upon the surface to be developed an alkalineliquid containing an azo-dyestufi' component and a buffer salt, in theform of a uniformly thin film.

3. The process for developing direct positive diazo prints whichconsists in impressing an alkaline liquid containing an azo-dyestuflcomponent in the form of a uniformly thin film upon an exposed surfacehaving a diazo compound therein, said film containing the azo-dyestuffcomponent in an amount not substantially in excess of that required tocouple with the diazo compound.

4. The process for developing direct positive diazo prints whichconsists in saturating throu hout its entire area the exposed surface 0said prints with a developing liquid containing a non-volatile alkalinesubstance by spreading said liquid on said surface in the form of auniformly thin film, the quantity of the developing liquid con. tainedin the film being substantially corre sponding to that required toeffect development of said surface.

, 5. The process for developing direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid con taining a non-volatile alkaliand a buffer salt by spreading said liquid on said surface in the formof a uniformly thin film, the quantity of the developin liquid containedin the film being substantia ly corresponding to that pequired to effectdevelopment of said surace.

6. The process for developing direct positive diazo prints whichconsists in saturating throu hout its entire area the exposed surface 0said prints with a developing liquid containin a non-volatile alkalinesubstance and a re ucing agent non-decomposable by alkali by spreadingsaid liquid on said surface in the form of a uniforml thin film, thequantity of the developing liquid contained in the film beingsubstantially corresponding to that required to effect development ofsaidcsurface.

7. The rocess according to claim 6 wherein the red iicing a cut is athiosulphate.

8. The process or developing direct positi ve (liazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid containing a non-volatile alkalinesubstance, an azo d estufi' com onent, and a reducing agent nonecomposabe by alkali by spreading said liquid on said surface in the form of auniformly thin film, the quantity of the developing liquid contained inthe film being substantially corresponding to that required to effectdevelopment of said surface.

9. The process according to claim 8 wherein the reducing agent isthiosulphate.

10. The process for developing direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid containing a non-volatile alkalinesubstance and a wetting agent by spreading said liquid on said surfacein the form of a uniformly thin film, the quantity of the developingliquid contained in the film being substantially corresponding to thatrequired to effect development of said surface.

11. The process for developing direct positive diazo prints containing adiazo compound of the type which can not be used together withazo-dycstutf components in the light sensitive layer which consists insaturating throughout its entire area the exposed surface of said printswith a developing liquid containing a non-volatile alkaline substanceand an azo-dycstnff component by spreading said liquid on said surfacein the form of a uniformly thin film, the quantity of the developingliquid contained in the film being substantially corresponding to thatrequired to effect development of said surface.

12. The process for developing direct positive diazo prints containing adiazo compound of the type which can not be used together withazo-dyestnll' components in the light sensitive layer which consists insaturating throughout its entire area the exposed surface of said printswith a developing liquid containing a non-volatile alkali, a buffersalt, and an azo-dyestufl' component by spreading said liquid on saidsurface in the form of a uniformly thin film, the quantity of thedeveloping liquid contained in the film being stantially correspondingto that required to efi'ect development of said surface.

14. The process for developing direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid containing a non-volatile alkaliand a buffer salt by momentarily wetting the exposed surface with anexcess of said developing liquid and removing the excess immediatelythereafter, so as to depose a uniformly thin film of said liquid to saidsurface, the quantity of the developing liquid contained in the filmbeing substantially corresponding to that required to effect developmentof said surface.

15. The process for developing direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid containing a non-volatile alkalinesubstance and a reducing agent non-decomposable by alkali by momentarilywetting the exposed surface with an excess of said developing liquid andremoving the excess immediately thereafter, so as to depose a uniformlythin film of said liquid to said surface, the quantity of the developingliquid contained in the film being substantially corresponding to thatrequired to effect development of said surface.

16. The process for developing direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid containing a non-volatile alkalinesubstance and an azodyestuif component by momentarily wetting theexposed surface with an excess of said developing liquid and removingthe excess immediately thereafter, so asto depose a uniformly thin filmof said liquid to said surface, the quantity of the developing liquidcontained in the film being substantially corresponding to that requiredto effect development of said Surface.

17. The process for developing direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid containing a non-volatile alkali, abuffer salt and an azodyestulf component by momentarily wetting theexposed surface with an excess of said developing liquid and removingthe excess immediately thereafter, so as to depose a uniformly thin filmof said liquid to said surface, the quantity of the developing liquidcontained in the film being substantially corresponding to that requiredto effect developmentof said surface.

18. The process for-developing direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with' a developing liquid containing a non-volatile alkalinesubstance, an azodyestufl' component and a reducing agentnon-decomposable by alkali by momentarily Wetting the exposed surfacewith an excess of said developing liquid and removing the excessimmediately thereafter, so as to depose a uniformly thin film of saidliquid to said surface, the quantity of the developing liquid containedin the film being substantially corresponding to that required to effectdevelopment of said surface.

19. The process for developing direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid containing a non-volatile alkalinesubstance, and a wetting agent by momentarily wetting the exposedsurface with an excess of said developing liquid and removing the excessimmediately thereafter, so as to depose a uniformly thin film of saidliquid to said surface, the quantity of the developing liquid containedin the film being substantially corresponding to that required to effectdevelopment of said surface.

In testimony whereof we affix our signatures.

Dr. LODEWIJK PIETER FRANS van der GRINTEN. Dr. KAREL JAN JOSEF van derGRINTEN.

Ring the excess immediately thereafter, so as to depose a uniformly thinfilm of said liquid to said surface, the quantity of the developingliquid contained in the film being sub stantially corresponding to thatrequired to effect development of said surface.

18. The process fordeveloping direct positive diazo prints whichconsists in saturating throughout its entire area the exposed surface ofsaid prints with a developing liquid containing a non-volatile alkalinesubstance, an azodyestuff component and a reducing agentnon-decomposable by alkali by momentarily Wetting the exposed surfacewith an excess of said developing liquid and removing the excessimmediately thereafter, so as to depose a uniformly thin film of saidliquid to said surface, the quantity of the developing liquid containedin the film being substantially corresponding to that required to effectdevelopment of said surface.

19. The process for developing direct positive diazo prints whichconsists in saturating throughout its entire area the ex osed surface ofsaid prints with a developlng liquid containing a non-Volatile alkalinesubstance, and a wetting agent by momentarily wetting the exposedsurface with an excess of said develo ing liquid and removing the excessimme lately thereafter, so as to depose a uniformly thin film of saidliquid to said surface, the quantity of the developing liquid containedin the film being substantially corresponding to that required to eflectdevelopment of said surface.

In testimony whereof we affix our signatures.

Dr. LODEWIJK PIETER FRANS van der GRINTEN. Dr. KAREI. JAN JOSEF van derGRINTEN.

DISCLAIMER 1,841,653.Lodewi'k Pieter Frans van der Grinten and Karel JanJosef van der PROCESS FOR DEVELOPING POSITIVE Dmzo 19, 1932. Disclaimerfiled September 12, runing Company, Inc.

Hereby enters its disclaimer of claims 7 and 9 of said patent.

Grinten, enlo, Netherlands. PRIN'rs. Patent dated Januar 1934, by theassignee, Charles [Qfl'icial Gazette October 9, 1934.]

DISCLAIMER 1,841,653.Lodewik Pieter Frans van der Grinten and KarGrinten, enlo, Netherlands. PROCESS PRINTS. Patent dated Janua 19, 1932.Disclaimer filed September 12, 1934, by the assignee, Charles rum'ngCompany, Inc.

Hereby enters its disclaimer of claims 7 and 9 of said patent. I GazetteOctober .9, 1934.]

el Jan Josef van der Fon DEVELOPING Posrnvn Dmzo

